An official OGC Best Practice document entitled, "OGC EO Product Collection, Service and Sensor Discovery using the CS-WebRIM Catalogue" was adopted by the Open Geospatial Consortium. This OGC Best Practices Document describes the relations that exist between several metadata conceptual models: Earth Observation (EO) Product, EO Product Collections, Sensors and Services. Specification of the linking between artifacts of these types is important for the process of cataloguing and discovering those artifacts.
During the Heterogeneous Missions Accessibility (HMA) series of projects managed by the European Space Agency (ESA), the HMA stakeholders defined a minimal set of metadata elements that are required to describe a collection of EO products. The stakeholders also defined a minimal set of metadata elements required to describe the different Web service instances that are being deployed throughout the Ground Segments of the Global Monitoring for Environment and Security (GMES) Contributing Missions.
The OGC EO Product Collection, Service and Sensor Discovery using the CS-W ebRIM Catalogue document is available and free to the public at http://www.opengeospatial.org/standards/bp.